1. Technical Field
The present invention relates generally to anti-lock brake systems, and particularly to a supervisory integrated circuit that is capable of inhibiting brake modulation in an anti-lock brake system when the circuit senses that certain monitored system parameters fall outside a predetermined window.
2. Discussion
In response to government regulations and increasing driver safety concerns, installation of anti-lock braking system (ABS) units in motor vehicles has increased steadily in recent years. As is well known, ABS units modulate vehicle brakes when the brakes are applied in an emergency braking situation or in a vehicle traction control situation. Typically, ABS units are regulated by an on-board ABS computer, which senses one of the above conditions when the brakes are applied, and modulates the brakes through solenoid actuated valves, or modulators. In tractor trailer trucks and other heavy duty vehicles with pneumatic brake systems, solenoids associated with brake modulators are energized when an emergency or traction control situation is sensed by the ABS computer, and the brake modulators open brake chambers or block the chamber air supplies in a modulating fashion so that vehicle braking is realized in an intermittent fashion.
The on-board ABS computer, in addition to controlling application of the ABS unit, also supports communication protocol between the ABS unit and other vehicle components and includes self-diagnostics capabilities. In order to discharge these basic functions, fundamental computer operating parameters must be maintained. If the computer operating parameters are not maintained within certain operating limits, less than optimal ABS unit performance could possibly result.